As a contact mechanism for opening/closing a current path, there has conventionally been proposed a switch, such as a circuit breaker or an electromagnetic contactor. In such a switch that generates an arc when cutting off a current, a fixed contact applied thereto is folded into a U-shape as viewed laterally, and a fixed contact point is formed on the folded part of the U-shape. Furthermore, a movable contact point of a movable contact is disposed on this fixed contact point so as to be capable of contacting with and separating from the fixed contact point. The switch increases an opening speed of the movable contact by increasing an electromagnetic repulsion that acts on the movable contact when cutting off a large current, to drastically expand the arc (see Patent Literature 1, for example).
There has also been proposed a contact structure of an electromagnetic contactor in which a magnetic field generated by a flowing current drives an arc in the same configuration as the configuration described above (see Patent Literature 2; for example).    Patent Literature 1: Japanese Patent Application Publication No. 2001-210170    Patent Literature 2: Japanese Patent Application Publication No. H4-123719
Incidentally, the prior art described in Patent Literature 1 increases an electromagnetic repulsion that is generated by forming the fixed contact into a U-shape as viewed laterally. The increased electromagnetic repulsion consequently increases the opening speed of the movable contact to drastically expand the arc, the opening speed being obtained when cutting off a large current generated due to short circuit and the like. In this manner, the value of an accidental current can be restricted to a small value.
However, the electromagnetic contactor that is combined with a fuse or a circuit breaker to configure a circuit is required to inhibit the electromagnetic repulsion from opening the movable contact when a large current is applied thereto due to short circuit. The prior art described in Patent Literature 2, therefore, satisfies the requirement by increasing a spring force of a contact spring for ensuring a contact pressure of the movable contact on the fixed contact.